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一、输入输出映射

Mapper.xml映射文件中定义了操作数据库的sql，每个sql是一个statement，映射文件是mybatis的核心。

1、parameterType(输入类型)

1.1、传递简答类型

参考第一天内容

使用#{}占位符，或者${}进行SQL拼接

1.2、传递pojo对象

参考第一天的内容

Mybatis使用OGNL表达式解析对象字段的值，#{}或者${}括号当中的值为pojo属性名称

1.3、传递pojo包装对象：创建包装的pojo对象QueryVo

package com.itzheng.mybatis.pojo;/* * 包装的pojo */public class QueryVo {
   	private User user;	public User getUser() {
   		return user;	}	public void setUser(User user) {
   		this.user = user;	}}

1.4、在UserMapper当中创建getUserByQueryVo方法

/*	 * 传递包装pojo	 */	List
   
     getUserByQueryVo(QueryVo vo);
   

1.5、在UserMapperTest类当中创建testGetUserByQueryVo方法

@Test	public void testGetUserByQueryVo() {
   		SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		// 获取接口的代理实现类		UserMapper userMapper = openSession.getMapper(UserMapper.class);		QueryVo vo = new QueryVo();		User user = new User();		user.setUsername("张");		vo.setUser(user);		List
   
     list = userMapper.getUserByQueryVo(vo);		for (User user2 : list) {
   			System.out.println(user2);		}		openSession.close();	}
   

运行测试

2、统计个数

（1）修改UserMapper.xml创建对应的内容

		SELECT COUNT(1) FROM `user`	

（2）创建对应的接口当中的方法

/*	 * 查询用户总记录数	 */	Integer getUserCount();

（3）在UserMapperTest类当中创建对应的方法

@Test	public void testGetUserByCount() {
   		SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		// 获取接口的代理实现类		UserMapper userMapper = openSession.getMapper(UserMapper.class);				System.out.println("用户总记录数为："+userCount);		System.out.println(userCount);				openSession.close();	}

运行测试结果

3、查询订单列表

（1）创建OrderMapper接口当中的getOrderList方法

package com.itzheng.mybatis.mapper;import java.util.List;import com.itzheng.mybatis.pojo.Order;/* * 订单的持久化接口 */public interface OrderMapper {
   	/*	 * 获取订单列表	 */	List
   
     getOrderList();}
   

（2）在OrderMapper.xml当中

   
   
   
   	
    		SELECT		  `id`,		  `user_id` userId,		  `number`,		  `createtime`,		  `note`		FROM `order`		
   

（3）创建单元测试包OrderMapperTest

package com.itzheng.mybatis.test;import java.util.List;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.junit.Test;import com.itzheng.mybatis.mapper.OrderMapper;import com.itzheng.mybatis.pojo.Order;import com.itzheng.mybatis.utils.SqlSessionFactoryUtils;public class OrderMapperTest {
   	@Test	public void testGetOrderList() {
   		SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		//获取OrderMapper代理实现		OrderMapper ordermapper = openSession.getMapper(OrderMapper.class);		List
   
     list = ordermapper.getOrderList();				for (Order order : list) {
   			System.out.println(order);		}		openSession.close();	}}
   

运行测试

4、resultMap

（1）修改OrderMapper.xml添加

   	
   		
    		
    		
    		
    		
    		
    		
    	
   	
   			SELECT		  `id`,		  `user_id`,		  `number`,		  `createtime`,		  `note`		FROM `order`	

（2）在OrderMapper接口当中创建getOrderListMap方法

List
   
     getOrderListMap();
   

测试运行

5、动态sql-if标签的使用（条件查询）

（1）修改UserMapper.xml

		SELECT 			id,			username,			birthday,			sex,			address 		FROM `user` 		
    		WHERE 1 = 1					and username LIKE '%${username}%'							and sex = #{sex}			

（2）在接口当中创建对应的方法

List
   
     getUserByPojo(User user);
   

（3）UserMapperTest当中创建对应的testGetUserByPojo方法

@Test	public void testGetUserByPojo() {
   		SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		// 获取接口的代理实现类		UserMapper userMapper = openSession.getMapper(UserMapper.class);				User user = new User();		user.setSex("1");		user.setUsername("张");		List
   
     userByPojo = userMapper.getUserByPojo(user);				for (User user2 : userByPojo) {
   			System.out.println(user2);		}				openSession.close();	}
   

运行测试

6、动态sql-sql片段的使用

（1）抽取SQL片段

   
    		id,		username,		birthday,		sex,		address 
   

（2）引用sql片段的id

   			SELECT 		
    				FROM 		USER WHERE id = #{id1}	

（3）运行测试代码

7、sql-foreach标签的使用：

(1)修改QueryVo类

(2)修改UserMapper.xml

				SELECT				FROM `user`		WHERE id IN(1,25,29,30,35)		

运行测试代码

8、（方式一）一对一关联查询

（1）创建OrderUser

package com.itzheng.mybatis.pojo;/* * 订单关联用户信息的pojo */public class OrderUser extends Order {
   			private String username;// 用户姓名		private String address;// 地址			public String getUsername() {
   		return username;	}	public void setUsername(String username) {
   		this.username = username;	}	public String getAddress() {
   		return address;	}	public void setAddress(String address) {
   		this.address = address;	}	@Override	public String toString() {
   		return "OrderUser [username=" + username + ", address=" + address + ", getUsername()=" + getUsername()				+ ", getAddress()=" + getAddress() + ", getId()=" + getId() + ", getUserId()=" + getUserId()				+ ", getNumber()=" + getNumber() + ", getCreatetime()=" + getCreatetime() + ", getNote()=" + getNote()				+ ", toString()=" + super.toString() + ", getClass()=" + getClass() + ", hashCode()=" + hashCode()				+ "]";	}}

（2）修改OrderMapper.xml

   				SELECT 				o.`id`, 				o.`user_id` userId, 				o.`number`, 				o.`createtime`, 				o.`note`,				u.`username`,				u.`address`			FROM   				 `order` o			LEFT JOIN `user` u  				ON u.id = o.user_id	

（3）OrderMapper接口当中创建getOrderUser方法

/*	 * 一对一关联：resultType使用	 */		List
   
     getOrderUser();
   

（4）OrderMapperTest当中编写测试方法testGetOrderUser

@Test	public void testGetOrderUser() {
   				SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		//获取OrderMapper代理实现		OrderMapper ordermapper = openSession.getMapper(OrderMapper.class);				List
   
     orderUser = ordermapper.getOrderUser();				for (OrderUser orderUser2 : orderUser) {
   			System.out.println(orderUser2);		}				openSession.close();	}
   

运行测试代码

9、（方式一）一对一关联查询:ResultMap：一个订单只有一个人

(1)修改Order

private User user;	public User getUser() {
   		return user;	}	public void setUser(User user) {
   		this.user = user;	}

(2)修改OrderMapper.xml

   		
    		
    		
    		
    		
    		
    		
    		
    		
    			
     			
     			
     			
     			
     		
    	
   	
   				SELECT 				o.`id`, 				o.`user_id` userId, 				o.`number`, 				o.`createtime`, 				o.`note`,				u.`username`,				u.`address`,				u.`birthday`,				u.`sex`			FROM   				 `order` o			LEFT JOIN `user` u  				ON u.id = o.user_id	

(3)在OrderMapper接口当中编写getOrderUserMap方法

/*	 * 一对一关联：ResultMap使用	 */	List
   
     getOrderUserMap();
   

(4)编写测试方法，然后运行

@Test	public void testGetOrderUserMap() {
   				SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		//获取OrderMapper代理实现		OrderMapper ordermapper = openSession.getMapper(OrderMapper.class);				List
   
     orderUserMap = ordermapper.getOrderUserMap();				for (Order order : orderUserMap) {
   			System.out.println(order);			System.out.println("	此订单的用户为：" + order.getUser());		}				openSession.close();	}
   

运行测试

10、（方式二）一对多关联查询：一个人有多个订单

（1）修改User

private List
   
     orders;	public List
    
      getOrders() {
   		return orders;	}	public void setOrders(List
     
       orders) {
   		this.orders = orders;	}
     
    
   

（2）修改UserMapper.xml

   		
    		
    		
    		
    		
    		
    		
    		
    			
     			
     			
     			
     			
     			
     			
     		
    	
   			SELECT 			u.`id`,			u.`username`,			u.`birthday`,			u.`sex`,			u.`address`,			u.`uuid2`,			o.`id` oid,			o.`number`,			o.`createtime`,			o.`note`		FROM			`user` u		LEFT JOIN `order` o		ON o.`user_id` = u.`id`	

（3）在UserMapper接口当中创建getUserOrderMap方法

（4）编写测试方法

@Test	public void testGetUserOrderMap() {
   		SqlSession openSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();		// 获取接口的代理实现类		UserMapper userMapper = openSession.getMapper(UserMapper.class);		List
   
     list = userMapper.getUserOrderMap();		for (User user2 : list) {
   			System.out.println(user2);						for (Order order : user2.getOrders()) {
   				System.out.println("	此用户的订单有："+order);			}		}		openSession.close();	}
   

总结

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